The present invention relates to the field of memory-programmable controllers of the type having cyclically traversed user control programs for controlling peripheral processes. In particular the present invention relates to memory-programmable controllers of the multiprocessor type having a word processor for processing operating system and word commands, a bit processor for processing binary interlinking commands, a user program memory in which the control program is stored, an operating system memory in which an operating system program is stored and a data memory wherein binary process images of the peripheral process under control are stored.
Memory-programmable controllers are described in detail, for instance, in Siemens Zeitschrift "Energietechnik" 1979, no. 2, pages 43 to 47 no. 4, pages 136 to 139 in European Patent No. 10170 and in U.S. Pat. Nos. 3,921,146 and 3,942,158.
A memory-programmable controller of the type mentioned above should preferably be able to carry out the logical interlinking of data 1-bit wide as well as more complex functions with data one word wide, such as arithmetic functions, data transfer, timing etc.
It is therefore advantageous to use within the scope of a memory programmable controller a multiprocessor system, in which the execution of binary commands is assigned to a separate bit processor, while a relatively slow word processor which processes bits in parallel can carry out more complex functions (see, for instance, Siemens Zeitschrift "Energietechnik" 1980, no. 9, page 361).
An essential criterion for a memory-programmable controller is that it process word and bit commands rapidly. In particular the bit processor must be able to process commands rapidly.